From the Germanic name Karl, which was derived from a Germanic word meaning "man". However, an alternative theory states that it is derived from the common Germanic elementhari meaning "army, warrior".

The popularity of the name in continental Europe was due to the fame of Charles the Great (742-814), commonly known as Charlemagne, a king of the Franks who came to rule over most of Europe. It was subsequently borne by several Holy Roman Emperors, as well as kings of France, Spain, Portugal, Sweden and Hungary. The name did not become common in Britain until the 17th century when it was carried by the Stuart king Charles I. It had been introduced into the Stuart royal family by Mary Queen of Scots, who had been raised in France.

Famous bearers of the name include naturalist Charles Darwin (1809-1882) who revolutionized biology with his theory of evolution, novelist Charles Dickens (1812-1870) who wrote such works as 'Great Expectations' and 'A Tale of Two Cities', French statesman Charles de Gaulle (1890-1970), and American cartoonist Charles Schulz (1922-2000), the creator of the 'Peanuts' comic strip.